
<form class="form-horizontal" action="export.php" method="post" name="upload_excel"   
                      enctype="multipart/form-data">
                  <div class="form-group">
                            <div class="col-md-4 col-md-offset-4">
                                <input type="submit" name="Export" class="btn btn-success" value="export to excel"/>
                            </div>
                   </div>                    
            </form>    
		